Fermi GBM Observations of LIGO Gravitational Wave event GW150914

Research output: Contribution to journalArticlepeer-review


  • V. Connaughton
  • C. M. Hui
  • P. Jenke
  • T. Littenberg
  • J. E. McEnery
  • J. Racusin
  • P. Shawhan
  • L. Singer
  • C. A. Wilson-Hodge
  • P. N. Bhat
  • E. Bissaldi
  • W. Cleveland
  • M. H. Gibby
  • A. von Kienlin
  • R. M. Kippen
  • S. McBreen
  • B. Mailyan
  • C. A. Meegan
  • W. S. Paciesas
  • O. Roberts
  • L. Sparke
  • M. Stanbro
  • K. Toelge
  • P. Veres

Colleges, School and Institutes


With an instantaneous view of 70% of the sky, the Fermi Gamma-ray Burst Monitor (GBM) is an excellent partner in the search for electromagnetic counterparts to gravitational wave (GW) events. GBM observations at the time of the Laser Interferometer Gravitational-wave Observatory (LIGO) event GW150914 reveal the presence of a weak transient above 50 keV, 0.4~s after the GW event, with a false alarm probability of 0.0022 (2.9$\sigma$). This weak transient lasting 1 s was not detected by any other instrument and does not appear connected with other previously known astrophysical, solar, terrestrial, or magnetospheric activity. Its localization is ill-constrained but consistent with the direction of GW150914. The duration and spectrum of the transient event are consistent with a weak short Gamma-Ray Burst arriving at a large angle to the direction in which Fermi was pointing, where the GBM detector response is not optimal. If the GBM transient is associated with GW150914, this electromagnetic signal from a stellar mass black hole binary merger is unexpected. We calculate a luminosity in hard X-ray emission between 1~keV and 10~MeV of $1.8^{+1.5}_{-1.0} \times 10^{49}$~erg~s$^{-1}$. Future joint observations of GW events by LIGO/Virgo and Fermi GBM could reveal whether the weak transient reported here is a plausible counterpart to GW150914 or a chance coincidence, and will further probe the connection between compact binary mergers and short Gamma-Ray Bursts.

Bibliographic note

Accepted for publication in ApJL


Original languageEnglish
JournalAstrophysical Journal Letters
Issue number1
Early online date11 Feb 2016
Publication statusPublished - 13 Jul 2016


  • astro-ph.HE